peter_mcc

It’s definitely possible – as others have said, it’s called an embedded network. Working out if you would save money overall is very complicated – large customers are charged very differently to smaller customers.

If the embedded network is run for the benefit of the owners it can be worthwhile – not every embedded network is bad. If it’s run by an external for-profit company who has to recoup their investment in meters/etc then they can be bad for the owners.

I’ve looked into it for my work strata building. For us there is the opportunity to add a 100kW solar system on the roof and then sell that power to owners via an embedded network. Pros are that the body corp gets retail rates for their solar (so 40c/kWh in peak times) rather than the feed in rates (10c or less).

Cons are that the overall billing depends a lot on the maximum demand charge. This is driven by the maximum usage in a 1/2hr peak period and then billed at that (or a higher) Rate for the next 12 months. So if you have one super hot summer’s day where everyone has their AC cranking at peak times and the solar is offline you end up with a massive maximum demand charge that you’re stuck with for the next 12 months.

If you’re serious about it my suggestion would be to install a 3 phase power monitor on the incoming mains to record the power usage for the next year or so. That will allow you to see what your maximum demand will be and that will allow you to get a better idea of the overall economics.

I think there is also an issue of any profits made being taxable in the hands of the individual owners but I’m not a lawyer and it all got too hard to understand very quickly.

I think the concern should be how to manage the electrical demands in the future. It isn’t just a matter of the first “X” get to install it – you also need to consider what will happen on a really hot (or cold) day when everyone is running their air conditioners at full power. If you exceed the rating on the main switchboard the fuses/main circuit breaker to the street may blow, taking out power to the whole building.

For my work building we have a 600A/phase feed from the substation. Most of the time (eg this week) we draw about 150A/phase during the day. But a few years ago after a string of really hot week days we hit 400A/phase. Still not enough to trip out the feed fuses. A few years before I arrived they managed to blow one phase fuse – it takes a while to get fixed because Ausgrid (the distributor) had to come.

I have no idea how you deal with it though in a practical sense. Most buildings have no visibility on how much power they are using and so there is no real way to say “we’re close to the limit, don’t charge your car”. If they were restricted to charging overnight (10pm – 6am) that would probably help since most poeople would be in bed and the sun has gone down, reducing the heat load.